Ments



C. G. SMITH ELECTRICAL APPARATUS March 1, 1932. Re. 18,368

Original Filed July 30, 1923 J Ja :3 9"

Reiuued 1, 1932 UNITED STATES PATENT oar-Ice;

CHARLES G. SMITH, OF MEDFOR-D, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGH- MENTS, TO RAYTHEON, IN, 0]? CAMBRIDGE, MASSACHUSETTS, A CORPORATION OF.

Original I0. 1,714,404, dated Kay 21, 1989, Serial No.

' filed May 21, 1981.

The present invention relates to electrical apparatus and more particularly to the type of electrical apparatus involving electrical conduction through a gaseous medium. I

The usual types of gaseous conduction apparatus employ a gaseous region having electrodes immersed therein, together with provision for impressing a sufficient potential difference between the electrodes to cause ionization and consequent-conduction in the gaseous region. Such prior constructions as have been placed upon the market ordinarily admit of simple electrical conduction between the electrodes and in some cases possess the property of rectifying alternating currents but in none of them, as far as I am aware, is it possible to obtain control of the gaseous conduction as is desirable for the amplification, modulation or production of electrical eous region which is caused to be electrically conducting upon the application of an electric field, together with means for distorting the ionization over a small portion of the gaseous region to alter the conductivity of the conducting gas as a'whole.

The operation of such a device may be briefly explained as follows: Electrical conduction in any gaseous medium is caused by the ionization of gas molecules by the impact of electrons against the molecules. Electrons impelled by the electric field collide with gas molecules, thus forming positive ions which in turn are also impelled by the electric field and are in themselves able to ionize other gas molecules by collision. ,Itvwill be seen that nuzcrmon. APPARATUS 654,648, filed July 30, 1928. Application for reiuu Serial No. 539,121.

the conducting condition of the gaseous conduction device arises principally from the progressive and cumulative ionizing action of the electrons and ions in the gas and that any attempts to arrest or distort this cumulative ionization is distorted over a small portion of the gaseous region de nds for its operatlon upon the principle 0 arresting the cumulative ionizing action in the gas.

Other features of the invention consist of certain novel features of construction, combinations and arrangement of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art from the following description.

In the accompanying drawings Figure 1 is a sectional elevation of an apparatus embodying the features of this invention; Fig. 2 is a section on line 2'2 of Fig. 1; Fig. 3 is a diagram of a type of telephone repeater circuit embodying one or more of the devices shown in Fig. 1; and Fig. 4: is a diagram of a simple circuit for the generation of electrical oscillations alsoembodying one of the devices of the present invention. a

The features of this invention are conveniently embodied in the type of apparatus disclosed in my Patent 1,545,207 granted July 7 1925. The above patent describes a novel type of insulating device comprising a pair of electrodes spaced sufiiciently close together in'a gaseous medium to normally limit the excursions of the electrons in the gas to distances which are so short that gaseous ionization is prevented. For the purposes of the present invention the gaseous medium is caused to become conducting through the action of forces which'tend to deflect the electrons in a sidewise direction between the electrodes inorder to lengthen their paths sufficiently to allow of collisions between the electrons and molecules of the gas. This is preferably effected by the employment of a magnetic field impressed in the gaseous region between the electrode surfaces. The use gion by means of an auxiliary electrode which maybe inserted in a space removed from one o of the main electrodes. The specific form of the invention to be presently described in detail employs electrodes having plane opposing surfaces but the principles of the invention may be obviously extended to include electrodes of any shape whatever.

Referring to the drawings, the invention Th in its preferred form consists of a receptacle 10, preferably of glass, containing a rarefied gas such as pure helium. Within the receptacle are located two main electrodes 7 and 8 having opposing plane surfaces located such a short distance apart that gaseous ionization is normally impossible. The proper distance between the electrodes is comparable to the mean free path of electrons in the gas, that is a distance such that electrons traveling directly across the gas space between the electrodes produce insuflicient ionization to initiate substantial conduction, the mean free path of the electrodes being understood to be the average distance traversed by the electrons without ionizing impact with gas molecules (or atoms). As shown in Fig. 1, the electrodes are made annular in form and are adapted to be supported upon a reentrant stem 17 of the receptacle 10. Electrode 7 is conveniently supported upon a constriction 17' of the stem and electrode 8 is supported by means of metallic straps 16 attached to the electrode and sealed into the top of the stem. The electrodes are so set up in the receptacle that the sides of the electrodes are spaced from the walls of the receptacle a distance 'which is of the order of magnitude of the distance separating the electrodes themselves, thus preventing ionization between the electrodes and the walls of the rtfie ptacle. The auxiliary electrode for the purpose of distorting the ionization consists of a supporting portion 11, and a depending portion 9. The s'iipporting portion 11, which is conveniently attached to the receptacle by means of metallic straps 18, has its exposed surfaces spaced so close to the 'surface of elect-rode 8 and to the walls of the receptacle that ionization is also precluded at those points. The depending portion 9 fits into a portion cut away from electrode 8, the plane surfaces of electrodes 8 and 9 being flush. As shown in Fig.

00 2, electrode 8 is provided with upstanding walls 15 completely surrounding electrode 9 and spaced sufliciently close thereto so that ionization in the region between electrodes 8 and 9 is impossible. It will be seen that according to the principles outlined in my Patgaseous region c .ternal'pole 6 and an external annular pole 5 adapted to set up a radial magnetic field in the region separated by the plane surfaces of the electrodes. For the purpose of connecting with external circuits, suitable lead wires 19 20 and 21 cooperating with electrodes 7, 8 and 9, respectively, are sealed into the receptacle. e lead wire 20 is conveniently passed through a hole in the pole 6 of the magnet. The action of ionization in this type of apparatus may be more readily understood by tracing what is believed to be the possible path of an electron in the gas.

Under the action of an electrical otential difference existing between electro es 7 and 8,-any free electrons in the gas are initially impelled in a direction practically normal to the electrode surfaces, but under the cooperating action of the magnetic field, the electrons are deflected so as to have a component of velocity parallel to the electrode surfaces. The electron paths are thus sufiiciently lengthened so that the number of collisions between the electrons and gas mole cules are greatly increased. On the plan view of the electrodes as shown in Fig. 2, for example, an electron starting at a follows approximately the path indicated by the dotted line and finally collides with a gas molecule at 11 forming a positive ion. The positive ion is impelled by the electric field against the cathode and due to its relatively large mass and low velocity, it is not sensibly de flected by the magnetic field. The impact of the ion against the cathode tendsv to liberate more electrons. It is not at present certain whether such an impact liberates one or more electrons or whether a number of such collisions are necessary to liberate even one electron, but for the purpose of explanation it will be assumed that each impact of a positive ion against the cathode liberates one electron. A liberated electron leaving from the point directly under I) is also deflected by the magnetic field, following the dotted line from 1) toward 0 where it collides with another gas molecule. The original electron is also present and is enabled to ionize other gas molecules of its own accord. It will be seen that the ionizing action takes place progressively and cumulatively around the electrodes and it is quite apparent that any interruption of thepro ressive action may seriously reduce the con ucting properties of the gaseous region asa whole. If the electrode 9 is maintained at the potential of elec-,

trode 8, .there is no such interruption of the progressive ionization and the device as a whole possesses conducting properties, but if the electrode 9 is disconnected or maintained at a otential approaching that of electrode 7, t e progressive action is interrupted and the ionization directly under electrode 9 is distorted. As, a result, the conducting properties of the entire device are materially weakened. The chief utility of the apparatus, however, lies in the fact that if'clectrode 9 undergoes variations of potential intermediate to the potentials of electrodes 7 and 8, the conductivity of the gaseous region between electrodes 7 and 8 is caused to vary in step with the potential of electrode 9. The device thus possesses the property of relay action and may be used in circuits for the amplification, generation, modulation or rectification of alternating currents.

When used as a device for operating upon electrical oscillations the two main electrodes of this apparatus are connected with a source of energy into an output circuit and the auxiliary electrode, together with one of the main electrodes, is connected into a circuit upon which the desired oscillations are impressed. The telephone repeater system shown in Fig. 3 is the usual type of two-way, two-element commonly known as the 22 type of system. It comprises two amplifying circuits, one for the amplification of currents traveling in one direction and the other for the amplification of currentstraveling in the other direction. In

each of these circuits is embodied an amplifying or repeating device. In Fig. 3, 30 and 31 represent, respectively, the tele hone lines leading into the repeater system. or the amplification of currents passing from line 30 to line 31, an amplifying system having an output circuit 15 is provided. This output circuit contains a source of direct current energy 12 and the main electrodes 7 and 8 of the device 10, previously described. The input circuit of the device is connected into line 30 in such a manner that the variations in potential in line 30 may be caused to vary the potential of electrode 9 with respect to that of 7 and 8. 'To this end, the input circuit is connected to electrodes 7 and 9. As previously stated, it may bedesirable to keep electrode 9 at an average potential intermediate to the potentials of electrodes 7 and 8 and for this purpose a battery 25 is provided. The magnetic means for lengthening the electron paths is designated gencrall at 6. An exactly similar system comprising an output circuit 15', amplifying tube'lO' and a battery 12', is connected into the line 31. The output circuit 15 contains the primary coils of transformers 35 and 33, the s-rcondaries of which are included in one of the wires of line 31. The other wire of line 31 contains inductance coils 37 similar to the transformer secondaries. Similar transformers and inductance coils 35', 36 and 37 cooperate with line 30. Lines 30 and 31 lead respectively into networks 32 and 33 which are artificial lines having as nearly as possible the same electrical characteristics as the lines 30 and 31 themselves. The input circuit from line 30 leading into electrodes 7 and 9 of the amplifier 10 is connected into line 30 at the junction points of inductances 35 and 36' and between the coils 37 as shown. The input circuit to amplifier 10' is connected in line 31 in an exactly similar manner. The operation of this system may be explained as follows: Electrical oscillations traveling to the right over line 30 divide a portion of their energy between network 32 and the output circuit of amplifier 10. That portion of the energy which passes into network 32 is lost and that portion which passes into the input circuit of the amplifier is multiplied and passed into line 31 through transformers 35 and 36. Of this amplified energy, one half passes to the right byline 31 and travels to its destination and the other half is absorbed by the network 33. If line 31 and net work 33 are perfectly balanced, it will be seen that no difference of potential can exist across the input circuit of amplifier 10 because of the balancing effect or Wheatst-one bridge action of the transformer coils and inductances 35, 36 and 37. If line 31 and network 33 are not perfectly balanced, a difference of potential will exist across electrodes 7 and 9 and this difference of otential will cause an amplified current toow in output circuit 15'. This amplified current will be transmitted into line 30 and if line 30 and network 32 are not perfectly balanced, another difference of potential will exist in the input circuit of tube 10. This constitutes a. feed back action and if the total unbalance is suflicient, undesirable oscillations will take place. It is therefore necessary that the networks be fairly well balanced with their respective lines. In the same manner energy traveling to the left over line 31 is amplified through tube 10 and circuit 15 and passed into line The oscillating system shown in Fi 4 depends upon the well known feed-bac principle, that is, the transfer of energy from the output back to the input circuit by means of some sort of coupling. As before, the output circuit contains a battery 12 and is con nected to electrodes 7 and 8 of the gaseous conduction device 10. Magnetic means indicated at 6 is employed for lengthening the electron paths to cause ionization to take place. The input circuit is connected between electrodes 7 and 9 and may contain an auxiliary source of energy 25. The two circuits may be coupled in any of the usual forms, that is, by electromagnetic, electrostatic or resistance couplings. The coupling is here shown as carried out by means of cooperating inductance coils 4.0 and 41 connected respectively inthe input and output circ uits. The frequenc of the produced oscillations s determine by tuning one of the c rcuits as is indicated in the present case, b inserting an inductance 26 and condenser 2 in the in at circuit. The oscillations may be utilize an a third .circuit 45 connected to the output circuit by a transformer46.

While it is preferred .to emplofy the specific construction and arrangement parts shown and described, it will be understood'that this construction and arrangement is not essen tial except so far as specified in the claims and may be changed or modified without departing from the broader features of the invent-ion.

' gas-filled receptacle The invention having been described, what is claimed is:

1. A method of controlling-the conducting,

properties of a gaseous medium between two electrodes spacedsufliciently close together to normally prevent gaseous ionization which consists in lengthening the paths of electrodes being comparable to the mean'free path of the electrons in the gas, means for lengthening the electron paths in a manner to cause progressive ionization around the electrode surfaces, and means for partially arresting the progressive action in aportion of the gaseous region.

4. A method of controlling the conducting propertiesof a gaseous medium between two electrodes which consists in causing electrons in a gas to take paths having a component of direction parallel to the electrode surfaces in a manner to cause progressiveionization to take place, and causin the progressive action to be partially nullified over a small portion of the electrode surfaces.

5. An electrical apparatus comprising two electrodes immersed in a gas, the distance between the electrode'surfaces being compar-- able to the mean free path of electrons in the gas, means for impressing a magnetic field to lengthen the electron paths and cause ionization of the gas, and means for distorting the ionization in a portion of the gaseous, region separating the electrodes.

6. An electrical apparatus comprising two electrodes immersed in a gas, the distance between the electrode surfaces being comparable to the mean free path of electrons in the gas, means for lengthening the electron paths to cause gaseous ionization, and an auxiliary- (electrode introduced into a portion of the gaseous region for the purpose of distorting the.

' to cause ionization of the gas, and an auxiliary electrodeintroduced into the gaseous region for the purpose of distorting the ionization in a manner to alter the conducting properties of the entire gaseous region.

8. An electrical apparatus comprising two electrodes immersed in a gas, the electrodes being so arranged relatively to one another that all electron paths in the gas are too short to allow of gaseous ionization, means for lengthenin the electron paths in a direction substantial y parallel to the electrode surfaces to cause progressive ionization, and means for partially arresting the progressive action at a point within the 'gaseous region.

9. Means for operating upon electrical occillations comprising a gaseous medium having one dimension comparable to the mean free path of electrons in the gas, means for cumulatively and progressively ionizingthe gas, and an input circuit cooperating with the gaseous medium and adapted to partially arrest the progr wsive ionizing action in the gas in a manner to vary the conductivity of the gas in' accordance with oscillations impressed upon the input circuit.

10. A system for amplifying-electrical os-f cillations comprising an output circuit and an input circuit, a pair of electrodes connected in the output circuit and immersed in a gaseous medium a distance apart comparable to the mean free path of electrons in the gas, a

source of energy in the out ut circuit, means for causing cumulative an progressive ionization around the electrodes, and a third electrode connected in the input circuit "and adapted to partially arrest the progressive ionizing action in the gas in a manner to vary the electrical characteristics of the output circuit in accordance with oscillations im-' pressed upon the input circuit.

11. A gaseous conduction device compris: in a sealed vessel containing an ionizable gas at ow pressure, and a pair of main electrodes having extended electrode surfaces disposed apart from each other within a distance of the order of the mean free path of electrons in the gas, means for producing conduction of electricity through the body of gas in the space between said electrodes, and an auxiliary electrode located adjacent one of said main electrodes within a distanceof the order of the mean free path of electrons in the gas .ranged in said vessel as and arranged to control the conduction in the space between said main electrodes by variation of potential applied to said-auxiliary electrode.

12. A gaseous discharge device comprising a sealed vessel containing an ionizable gas at low pressure, and a pair of main electrodes having extended electrode surfaces disposed apart within a distance too short to permit gaseous ionization by the potential applied therebetween, said electrodes being so ar to block the paths therebetween that are sufficiently long to pro duceionization at' the applied potential,

means for effecting conduction of electricity through'the body of gas in the space between said main electrodes, trode located adjacent one of said main electrodesfwithin a distance too short to permit ionization of the gas by the potential applied therebetween, said auxiliary electrode being arranged to control the conduction of the space between said main electrodes by variation of the potential applied thereto.

13., A gaseous discharge device comprising a sealed vessel containing-an ionizable gas at low pressure, a first electrode having an extended electrode surface, a second elecelectrode and said second --first electrode and trode and said second trode'having an extended electrode surface disposed away from the electrode surface of said first electrode within a distance too short to permit gaseous ionization by the potentialapplied therebetween, a source of current serially connected between said first electrode, said electrodes being so arranged within said vessel as to block ionization of the gas along paths between said electrodes that are sufiiciently long to produce ionization under the potential applied to said electrodes in operation, means for effecting conduction of electricity from said source through the body of gas between the electrodes, and an additional electrode located adjacent said first electrode within a distance too short to permit ionization of the gas under the applied voltage, said addi- "tional electrode belng arranged tovary the conduction in the space between said first electrode and said second electrode by the variation of potential applied between said said additional electrode.

14. A gaseous discharge device comprising a sealed vessel containing an ionizable gas at ow pressure, a first electrode havin an extended electrode'surface, a second e ectrode having an extended electrode surface disposed away from the electrodesurfaceof said first electrode within a distance too short to permit gaseous ionization by a potential applied therebetween, a source of current and an auxiliary elecelectrode surfaces of said between said electrodes that are sufliciently long to produce ionization under the potential applied to said electrodes in operation,

means for producing a magnetic field efi'ecting conduction of electricity from said source through the body of gas between the electrode surfaces of'said electrodes, and an additional electrode located adjacent said first electrode within a distance too short to permit ionization of the gas under applied voltage, said additional electrode being arranged to var the conduction in the space between said rst electrode and said second electrode by the variation of potential applied between said first electrode and said additional electrode.

15. A gaseous conduction device comprising a sealed vessel containing an 'ionizable gas at low pressure, and a pair of main electrodes having extended electrode surfaces disposed apart from each other within a,"

electrons in the vessel from entering into paths between the electrodes long enough to be broken down by the voltages applied to the electrodes.

In testimony whereof, I have hereunto subscribed my name this 19th day of May,

CHARLES o. SMITH.

serially connected" between said first elec-' trodes being so arranged within said vessel as to block ionization of the gas along paths electrode, said elec- 

